can thus be conceived as a fairly wide, upright, WNW-ESE-striking shear zone. Dextral shear criteria can be found in all of its formations. Asymmetrically deformed quartz pebbles in conglomeratic layers of the Thiviers sandstone indicate dextral shearing. The same sense of movement is even more evident in the Génis porphyroid, where pressure shadows have formed around the quartz and alkali feldspar phenocrysts. Millimetre-sized shear bands within the Génis sericite schist also point at dextral shearing. The timing of the shearing motions is based on comparisons with similar terrains in the Armorican Massif (Chantonnay synform in the Vendée) and in the Rouergue. The dextral shearing in the Armorican Massif is dated as Namurian and Westphalian (Serpukhovian till Moscovian), i.e. 325 to 305 million years ago. It is therefore reasonable to assume a mid- to late Carboniferous age for the deformations in the Génis Unit of the southern Limousin. The pervasive shearing motions are also responsible for the fold structures in the Génis Unit, which can be interpreted as tear folds caused by the transpressive, ductile wrenching. References Sources BRGM. Feuille Juillac. Carte géologique de la France à 1/50 000 Peterlongo, J.M. (1978). Massif Central. Guides Géologiques Régionaux. Masson. Roig, J.-Y., Faure, M. & Ledru, P. (1996). Polyphase wrench tectonics in the southern French Massif Central: kinematic inferences from pre- and syntectonic granitoids. Geologische Rundschau, 85, pp. 138–153 Geology of France